Plasticizing polyvinyl chloride



Petented Oct. 9, 1945 NlTED STATES PATENT orrlcs PLASTICIZIN G POLYVINYL CHLORIDE Edmund R. Meincke, Akron, Ohio, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application November 8, 1943, Serial No. 509,488

8 Claims.

wherein R is a residue of a polyhydric alcohol of the group consisting of alkylene glycols contain ing 2-4 carbon atoms, polyalkylene glycols containing 4-8 carbon atoms, glycerol, and pentaerythritol, X is the residue of 3,6-endomethylene- A-4,5-tetrahydrophtha1ic acid, Y is an alkyl group containing not more than 8 carbon atoms, and. n represents the integers, 2, 3 and 4.

This application is a continuation-in-part of my application Serial No. 417,824, filed November 4,1941.

For brevity and ease of expression, the 3,6- cndomethy1ene-4,S-tetrahydrophthalic acid will hereinafter be referred to as the tetrahydrophthalic acid, the context permitting.

In the above formula R may be the residue of ethylene, propylene or butylene glycol or of diethylene, dipropylene or dibutylene glycol or of trimethylene, tetramethylene or triethylene glycol. Where R is the residue of one of the dihydric alcohols, X represents the residue of each of two molecules of the tetrahydrophthalic acid,

ate) and tetrabutyl pentaerythritol tetrakis(3,6- endomethylene-A-4,5-tetrahydrophthalate) The mixed ester plasticizers are relatively high boiling point liquids and may be prepared as follows:

Example 1 The dibutyl ester of ethylene glycol bis(3,6- endomethylene-A-4,S-tetrahydrophthalic acid) may be prepared by heating a mixture of 5 mols 3,6-endomethylene-A-4,5-tetrahydrophthalic acid anhydride with 2.5 mols ethylene glycol at a ternperature of about 135 C. for about minutes.

one carboxyl group of each molecule of the tetrahydrophthalic acid being esterifled with one hydroxyl group of the glycol or polyalkylene glycol. Where Ris the residue of the trihydric alcohol, glycerol, or of the tetrahydric alcohol, pentaerythrltol, X represent the residue of each of 3 or 4 molecules of the tetrahydrophthalic acid respectively, one carboxyl group of each molecule of the tetrahydrophthalic acid being esterified with one About eight mols butyl alcohol is then added, preferably with a small amount of sulfuric acid as an esterification catalyst, and heating is continued for about two or three hours additional. The resulting mixed ester may be purified by distilling off excess alcohol under vacuum and then washing wtih dilute alkali and water ,to remove sulfuric acid. If desired, the product may be treated with decolorizing carbon and dilute potassium permanganate. The resultant product is a brownish liquid.

similarlmpthelimixed esters may be prepared by substituting "other alcohols for the butyl alco-- hol set forth in Example 1. Likewise, any of the other glycols mentioned may be substituted for the ethylene glycol of Example 1.- Other esterification catalysts may be usedin place of the sulfuric acid.

In the practice of the invention, the polyvinyl chloride is plasticized by thoroughly mixing it at elevated temperatures with one or more of the tetrahydrophthalic acid esters, a suitable quantity of plasticizer being, for example, about of the polyvinyl chloride by volume. The mixing may be done in any suitable manner, one method being to form a simple mixture of the polyvinyl chloride and plasticizer followed by a. more eiilcient blending of this mixture in a heated mixing apparatus. The mixing apparatus may be an open mill or an internal mixer. Where an open mill is employed, the heated rolls are tightly set and the simple mixture added gradually thereto and passed once therethrough'. The resulting flake-like product is collected and returned to the tightlyset rolls and milled there on until a continuous sheet of the mixture is formed. The rolls are then gradually opened to allow the mixture to build up a rollin bank of relatively small diameter and milling continued until the polyvinyl chloride is plasticized to the desired extent.

The invention is further illustrated by the following specific example to which, however, it is not intended that the invention be restricted.

Example 2 One hundred volumes of polyvinyl chloride were stirred with 89 volumes of dibutyl ethylene glycol bis(3,6-endomethylene-A-4,5-tetrahydrophthalate) This mixture was gradually fed onto a 6" x 12" open mill, the rolls of which. were tightly set and heated to 115 C. After having 1 passed the mixture once through the rolls, the resulting flaky product was collected and returned to the tightly set rolls. A continuous sheet of the mixture was formedin a milling time of about minute. The rolls were then gradually opened to allow the mixture to form a rolling bank of about /4" diameter and a translucent sheet of plasticized polyvinyl chloride was obtained in a total an elongation of 265%. It is obvious that the products of the present invention give plasticized compositions having outstanding physical properties.

The tetrahydrophthalic acid esters may be employed alone as plasticizers for polyvinyl chloride or they may be used along with the like mixed esters of phthalic acid which are described as plasticizers for polyvinyl chloride in my copending application, Ser.' No. 417,823 filed November 4, 1941.

The quantity of plasticizer may be varied, and as well, also, the temperature andlength of time of mixing. In general, these interrelated factors will be governed by the eillcie'ncy of the plasticizer selected. The efiiciency of the plasticizers may beincreased by raising the mixing temperature. The mixing time will vary also, of course, with the size of the batch.

The plasticized polyvinyl chloride compositions of the present invention may be used wherever polyvinyl chloride compositions of similar character are now used, such as in thewater proofing of fabrics and in the production of calendered, extruded and molded articles. The compositions may be colored with pigments or dyes and contain fillers.

The process of the invention extends also to the plasticizing o1 polyvinyl chloride containing polyvinyl acetate or other polymerized aliphthatic acid vinyl ester whether the latter are in mechanical mixture with the polyvinylchloride or have been copolymerized therewith.

Suitable modifications and changhs may be made in the invention without departing from the spirit and scope thereof, the foregoing description of the invention being intended by way of illustration except as may be defined in the appended claims.

I claim:

1. A composition comprising polyvinyl chloride plasticized with a mixed ester of the general for mula R(XY) 1:

wherein R is the esterifying residue ot a polyhydroxy alcohol of the group consisting of aikylene glycols containing 2-4 carbon atoms, polyalkylene glycols containing 4-8 carbon atoms, glycerol and pentaerythritol, X is the residue of 3,6 endomethylene A 4,5 tetrahydrophthalic acid, Y is an esterifying alkyl group containing not more than 8 carbon atoms and n is an integer equal to the number of hydroxyl groups in the alcohol of which R is the residue.

2. A composition comprising polyvinyl chloride wherein R. is the esterifying residue of a polyhydric alcohol of the group consisting of alkylene glycols containing 2-4 carbon atoms, polyalkylene glycols containing 4-8 carbon atoms, glycerol and pentaerythritol, X is the residue of 3,6-endomethylene-A-4,5-tetrahydrophtha1ic acid, Y is an esterifying alkyl group containing not more than 8 carbon atoms, and n is an integer equal to the number of hydroxyl groups in the alcohol of which R is the residue.

6. A process which comprises platiclzing polyvinyl chloride by mixing therewith-under the application of heat dibutyl ethylene glycol bis(3,6- endomethylene-A-4,5-tetrahyckophthalate) 7. A process which comprises plasticizing polyvinyl chloride by mixing therewith under the application of heat dibutyl diethylene glycol bis(3,6- endomethylene-A-4,B-tetrahydrophthalate) 8. A process which comprises plasticizing polyvinyl chloride by mixing therewith under the application of heat tributyl glycerol tris(3,6-end0- 

